In order to control the flight and other operational characteristics of an unmanned air vehicle, such as a missile, a conventional missile includes a significant amount of control electronics. Among other things, the control electronics control the flight of the missile by selectively activating the valves that propel and direct the missile toward its target. In this regard, the control electronics control valves which are designed to obtain fuel from the combustion chambers. In addition, the control electronics direct the operation of a number of sensors and other instruments which aid in the guidance of the missile as well as the operation of communications equipment. Additionally, the control electronics typically activates the batteries associated with the on-board electrical equipment, such as sensors, instruments, communications equipment and the like, in order to activate the on-board electrical equipment. Likewise, the control electronics typically squib the pressure tanks in order to build pressure in the fuel tank and the oxidizer tank.
Conventionally, the control circuitry of missiles or other unmanned air vehicles includes separate driver circuits, each of which typically includes a separate controller, for providing control signals to respective electrical subsystems. For example, separate driver circuits are generally associated with each valve in order to control the associated thrust. In this regard, a valve driver circuit would typically provide signals to the solenoid of the respective valve that cause the valve to open or close. In instances in which the valve is open, a mixture of a fuel with an oxidizer is typically provided from the combustion chamber which causes the missile to be propelled in a desired direction. Alternatively, in instances in which the valve is closed, fuel is no longer provided from the combustion chamber and no further propulsion is provided. Since more current is generally required in order to initially open a valve as opposed to maintaining a valve in an open position, the control electronics associated with the valve of each engine preferably initially provides a pull-in current in order to open the valve and then subsequently provides a hold current, which is significantly less than the pull-in current, in order to maintain the valve in the open position.
In addition to the separate driver circuits that are typically required for the solonoid of each valve, separate driver circuits are typically required for actuating each ordnance or squib carried by the missile. In this regard, ordnances or squibs are typically associated with batteries carried by the missile such that the actuation of an ordnance activates the respective battery which, in turn, provide power to an associated electrical subsystem, such as a sensor, an instrument, communications equipment or the like. In addition, ordnances or squibs can be disposed between the pressure tanks and the fuel tank and the oxidizer tank in order to cause the fuel and oxidizer tanks to be pressurized upon actuating of the ordnances.
As will be apparent, unmanned air vehicles, such as missiles, typically have stringent restrictions on the maximum permissible weight that can be carried without hampering its performance. Likewise, unmanned air vehicles have only a limited volume to house its various components as well as the fuel required for propulsion.
However, since separate driver circuits are typically provided for each valve and each ordnance, the control electronics of a conventional unmanned air vehicle are unfortunately relatively heavy and occupy a significant amount of space. In order to reduce the weight of the control electronics and to reduce the space consumed by the control electronics, a multi-channel driver circuit has been developed for controlling a plurality of valves. In this regard, the multi-channel driver circuit includes a plurality of valve drivers associated with respective valves and operating under control of a common controller, such as a programmable logic device. As such, the multi-channel driver circuit can individually actuate each valve, in order to open the valve and provide fuel to the respective engine. In particular, each valve driver can provide a pull-in current for a predetermined pull-in time in order to initially open the valve and can then provide a reduced level of current, namely, a hold current, for the remainder of the period during which the valve is held in an open position. Depending on the application, the pull-in current, the hold current, and the respective times for providing the pull-in current and the hold current can be individually set for each valve.
While the multi-channel driver circuit for controlling a plurality of valves does assist in reducing the weight of the control electronics and correspondingly reducing the space consumed by the control electronics, separate driver circuits are still required for controllably actuating the plurality of ordnances since ordnances have different current requirements for actuation than the valves. In this regard, ordnances typically require a pulse of relatively high current, such as 4 amps minimum, while a valve typically requires the application of a pull-in current that is significantly lower than the pulse of current provided to an ordnance, such as 1.8 amps in most cases, followed by the provision of an even lower hold current, such as 0.8 amps, for the remainder of the time that the valve is open. As such, a need still exists to reduce the weight of the control electronics onboard a missile or other unmanned air vehicle and to reduce the space consumed by the control electronics onboard a missile or other unmanned air vehicle.